[Public-List] rigging

[Don Campbell]

    There has been an extensive discussion on mast beams and rigging and 
the pros and cons of various rigging systems. The over-riding 
consideration in any refit is safety and it is never the safety of the 
conditions that one decides to sail out of port in,  but the conditions 
that one gets caught in while out that usually determine the maximum 
loading that we put our boats under. It has been shown many times that 
boats will take more than people in most of these circumstances so 
whatever the designer has done to make boats so they will weather a 
storm, they have done a fairly good job. However, they have done this 
using design principles which involve numbers and algorithms that 
dictate working load limits (WLL) and breaking load limits. Usually, we 
do not have those numbers at hand when we make decisions to repair or 
replace. The best we can do is look at materials for sale that seem to 
match what is there. We can also use recommended safety factors of 5x 
for loads not having to do with lifting people and 10x load if we are 
lifting people. That sets breaking loads at 5 x the WWL (so if you 
tension the rigging to 1000 lbs, you will need 5000 lb wire to be at 
that safety factor) and somewhere around 2500lbs if we are lifting 
people. Oversizing line is never a problem but it will put the breaking 
point of the system on whatever the next weakest link is.(chainplate bolts?)
    As an example problem of choices, the Harken catalogue gives 
measurements of breaking strengths of three 1/4" SS 1-19 wires: 302 is 
8200 lbs, 316 dyform is 8844 lbs and 316 is 7090 lbs. I suggest that not 
many of us could tell the difference by looking at these three wire 
ropes and I have a suspicion that there are few of us who could say what 
Whitby originally put on our boat or what is on our boat now if we have 
replaced the rigging..
    I have taught the ropes and knots materials for the Canadian Power 
and Sail course for a number of years and what I tell my students every 
time is to know what you need and know what you are buying by 
manufacturers specifications given on the materials that you buy. If 
there are no specs given on the roll of rope, then you don't know if the 
roll of rope is first grade or seconds. Knowing what you need is not 
just 1/4" wire rope. It is what spec on 1/4" wire rope you feel will be 
safe ( I'm not a lawyer) for the worst conditions you will ever be out 
in and then will that provide the WLL or breaking strength that the 
designer has given in his drawings.
    I never rely on price to tell me what the value is of the product. 
Most often we get what we pay for. There are many times I have gone to 
commercial riggers - the people who do the rigging for cranes and 
commercial lifting devices - for wire rope because they always have the 
specs and usually do not price things with BOAT in mind. That way, I 
know what I am getting when I buy wire rope from them..
    Therefore the questions that I would ask you to sort out are do you 
know the design requirements for the products you are fixing or 
replacing? and  does the product you are making or buying meet those 
specifications? If the answer for the second is that you don't know or 
that that product does not measure up to design requirement,  my 
recommendation is DON"T BUY IT!
    We have been given 2 figures on rigging in this recent discussion, 
$1000, from a source in Florida and $2000 from others. What we don't 
know is whether  both  rigging purchases contain the same components for 
a start. If one is done with Nico press fitting and the other with 
Norsemen fittings, there is one difference. If turnbuckles were replaced 
in one but not the other is another significant difference. Make sure 
you know what comparative pricing does for you, and if you do go for a 
group purchase, make sure you get a well described spec list before you 
tender it. That way, your comparative pricing will be effective.

Don #528 and #469

Jonathan Adams wrote:
> All,
>
> Mike and I have been communicating regarding a group buy of rigging material either fabricated or just the materials. If there are folks interested in participating in this, let me know.
>
> Also note that Gordon Laco has rigging material at great prices for A30 members - I got my turnbuckles through him.
>
> Jonathan
>
>
>
>
> ________________________________
> From: Richard Cronk <manan at nb.sympatico.ca>
> To: Public-List at lists.alberg30.org
> Sent: Mon, January 18, 2010 7:15:19 AM
> Subject: [Public-List] rigging
>
> Try Mac sails in Fla for rigging ..Got mine there and was  1/4 inch  with fitting  ..less than 1000;00
> D
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